About D. P. S. T. G.

B. W. A. N. Baddewithana

Rubber Research Institute of Sri Lanka, LK

About B. W. A. N.

Abstract

Systematic characterization of rubber (Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg.) clones based on their molecular diversity, and identification of molecular markers useful for characterization of rubber clones are vital in crop management systems and research. This study was undertaken to estimate the molecular diversity present among the Sri Lankan rubber clones and to determine the importance of molecular markers in categorizing different clones into distinct groups. Thirty eight rubber clones were screened using pre-selected 27 RAPD primers out of which five primers namely, OPC 04, OPA 18, OPB 18, OPA 20 and OPS 02 that produced more than three discrete bands on an average were used to assess the genetic diversity of rubber clones. These five primers generated high level of polymorphism among the clones. The number of alleles detected by different primers ranged from 1 to 8 with an average of 6 alleles per primer and the level of polymorphism was 100 %. The genetic distance values based on RAPD analysis ranged between 0.157 and 1.000. The resultant Nei's distance matrices were used to create clusters with UPGMA clustering method. Out of the 38 Hevea clones, three clones namely, PB 217, RRISL 201 and RRISL 226 could not be included due to lack of bands (less than three). The remaining 35 clones were grouped into seven main clusters at nearly 85 % distance level. The cluster size ranged from 1 to 16. The RAPD primers OPB 18 and OPS 02 were identified as suitable primers for genetic differentiation of the recommended H. brasiliensis clones. A key was constructed to identify the 35 clones using RAPD assay.